It is known in an automotive vehicle, in a collision event, to deploy an inflatable cushion, commonly referred to as an airbag, to protect vehicle occupants. Gas for deploying the airbag is supplied by an inflator bottle. One type of inflator bottle comprises a combustible gas mixture. A suitable combustible gas mixture comprises hydrogen, oxygen, argon, and helium gases. During deployment, the combustible gas mixture is ignited to form a product gas that is released through a nozzle into the airbag. Prior to deployment, a burst disk blocks a passage in the nozzle to contain the gas in the inflator bottle. During the early stages of ignition, the increase in pressure ruptures the burst disk to release the product gas. However, it is found that uncontrolled combustion of the combustible gas mixture requires a housing having thicker walls in order to prevent rupture due to the high pressures and the resultant improper deployment of the airbag due to the loss of inflation or product gas. Thicker housing walls undesirably add cost and weight to the inflator bottle. Also, uncontrolled combustion tends to increase the temperature of the product gas beyond limits for safe deployment in contact with the occupant. Moreover, in some applications, it may be desired to provide a more controlled release of product gas over an extended period of time as opposed to a rapid release such as would be produced by uncontrolled combustion of the combustible gas mixture.
Therefore, what is needed is an improved inflator bottle that is reliable to ignite the combustible gas mixture to produce an initial pressure effective to rupture the burst disk and release product gas through the nozzle, and thereafter to provide a controlled, sustained release of product gas at lower pressures and temperatures to deploy the airbag.